A substrate separation detection device has been used for use in a substrate processing apparatus that processes a substrate by continuously rotating a rotary table in a state in which a substrate is mounted in a substrate mounting recess formed on a surface of the rotary table that is provided inside a chamber in a substantially horizontal posture. The substrate separation detection device includes a substrate separation determination means that determines the separation of the substrate from the recess by determining the presence or absence of the substrate in the recess during rotation of the rotary table.
In such a substrate separation detection device, a radiation thermometer is used to detect temperatures at through holes for lift pins formed in the substrate mounting recess formed in the rotary table. Separation of the substrate is detected by a difference between the detected temperatures. Alternatively, separation of the substrate is detected by an imaging means installed to capture an image of the recess. If a determination is made that the substrate is separated, the rotation of the rotary table is stopped.
However, in the configuration described above, even though the occurrence of separation of the substrate can be detected, it is not possible to predict the separation of the substrate. Thus, this type of detection method is an ex-post measure. Although the damage in the chamber, the generation of defective wafers, and the like can be reduced, it is impossible to completely avoid damage.